eqpkinson



(No Model.) 3 Sheets-Sheet l. J. HOPKINSON 8a A. MUIRHEAD.

DYNAMO ELECTRIC MACHINE.

No. 280,039. Patented June 26, 1883..

(No Model.)

l 3 Sheets-Sheet 2. J. HPKINSON 8E MUIRHBAD.

DYNAMO ELECTRIC MAHINE. K

No. 280,039. Patented June 26, 1883.

(No Model.) 3 Sheets-Sheet 3. J. HOPKINSON 8v A. MUIRHEAD. DNAMo ELECTRIC MAGHINE. No. 280,039. Patented June Z6, 1888.

. 'I Ihm, @7g4 7%/ i@ FIG. 9.

l 4of the armature, we construct the armature NITED STATES JOHN HOPK'INSON PATENT FFICE.

AND ALEXANDER MUIRHEAD, OF VESTMINSTER,

, ENG-LAND.

\ .,DYNAMO-ELECTRIC MACHINE.

'.PECIFICATION forming* part of Letters Patent No. 280,039, dated June 26, 1883.

Application filed November 1852. (No model.) Patented in England November 24, 1880, No. 11,-86; in France May 2l, 18:21, No. 142,961,11111 in India December 5,1881, No. 152.

To all wh/om it may concern:

Be it known that we, JOHN Hornnvson and ALEXANDER MUIRHEAD, subjects ofthe Queen. of Great Britain, residing, respectively, at 4 Vestminster Chambers and 27 Regency Street, both in the city of WTest-minster, England, have invented certain new and useful Improvements in Dynamo-Electric Machines, (for which we have received Letters Patent in Great Britain, No. 4, 886, dated November 24, 1880, in France, No. 142,961, dated May 21, 1881, and in India, No. 152, dated December 5, 1881,) of whichv the following is a specification.

This invention has for its object improvements in dynamo-electric machines. To reduce the sparks which occur between the commutator and the collecting-brushes, we divide the collecting-brush .into parts, and that part which is latest in contact with any sectionvof the commutator passes the current through a resistance, thus gradually checking the current as the contact is brokein The same efiect may be obtained by interposing equivalent resistances in the commutator itsell". There the arrangement of the machine is such that the armature-coils lie in planes parallel or nearly parallel with the plane ofdrevolution thus: The circumference of a pulley is surrounded with a series of layers of sheet-iron insulated more or less completely from each other. On'one or both sides of the ring thus formed radial slots are cut to admit the coils of -insulated wire, which thus lie in planes parallel with the plane of revolution of the pulley. Then a continuous current is required, we place coils on both faces of the armature and arrange them alternately, so that when one coil is at its dead-point those near to it on the opposite face are producing their maximum ei'- i'ect. rPhe iield-magnets are made in a manner similar to the armature, though not necessarily with precisely the same number of coils; but it is cheaper to make their cores of solid wrought-iron. In some cases we construct them of cast-iron. It is advantageous to cut grooves in the face of the iron and to iill up the grooves with insulated sheet-iron, so stopping the local currents in the cores, which would otherwise occur. Both in the armature and in the magnets we pack each coil close against its neighbor. Each coil is thus ot' approximately quadrilateral form.

In order that our sai d invention may be most fully understood and readily carried into eitect, we will proceed to describe the drawings hereunto annexed.

ln the drawings, Figures 1 and 2 show a convenient method by which, according to our invention, to reduce the sparks which occur between the commutator and the collecting-brushes in continuous-current machines. a. a (l. are the segments of the commutator, insulated from each other. b b l) are the collecting-brushes or their equivalents, carried on a spi ndle, c. One of th cse brushes, bf, is arranged in sucl 1r wise that thereis an electrical resistance between the brush b and the spindle c. This resistance may be made in various ways, but we prefer that shown in Fig. 2 of the drawings. d e are metal cylinders. To d the brush is attached, while c is in contact with. the spindle c.

- rlhe space f between (l and c is iilled with a mixture of plumbago and lamp-black having a suitable resistance. The ends of the space f are closed with disks of ivory. The brush b is so adjusted, by lengthening, or as shown inFig. 11, or otherwise, that it remains in contact with any segment of the commutator for a short space after the other brushes have left contact with that segment. The effect is that, instead oi' sudden rupture of the continuity or' the armature-circuit connected to the segment of the commutator, a resistance is iirst introduced, and contact is not broken till the current has been in some measure reduced. For the more convenient adjustment of .the machine, we provide several sets of brushes having different resistances, and we ascertain b v trial and use that which gives the best result. instead ot' interposing a resistance between the brush 1/ and the spindle c, the commutatorplate may be divided into two parts separated by an appropriate resistance, as illustratedin Eig. 11. It is clear that the electrical. effect will be the same as in the plan more particularly described, and which we prefer. The collector or commutator which is used when a continuous current is desired we make with the metal pieces to which the wires ot' the armaturev are connected air-insulated. The metal pieces are carried on insulating-disks at their ends, only having air-insulation in that part on which t-he cOllectingbiuShes or their equivalents rub.

Figs. 3 and 4f show the armature we use in .machines arranged so that the coils lie in planes parallel or nearly parallel with the plane oi' revolution oi.' the armature. g is apulley to be keyed on the shaft ot' the machine. lt is surrounded by a series ot' layers, l1, ot' sheet-iron, more or less insulated from each other. ln one or both faces ot' this ring of layers ot` iron radial slots are eut i'or the reception ot'the coils ot' insulated wire fi. The best method ot' iixing the layers Aot' iron we believe to be the :following: On the pulley we coil a band of sheet-iron and ot' asbestus paper, so that the asbestus paper separates the successive layers oi' iron from each other. \V hen a sufficient thickness has been obtained, radial holes are drilled and bolts 7.' are inserted and secured by the cotters 7.1. lt' the bolts are put in and cottered hot, the layers otl iron and paper are very lirmly nipped onto the pulley. The radial slots may now be cut. lhe iigures show the armature as arranged t'or a continuous current-that is, with the slots on one side half-way between the slots on the other side ot" the armature. This is done in order that the current may be more approximately continuous; but when an alternating` current is desired the slots in the opposite Afaces correspond. rlhe connections ofthe coils with. each other may be varied according to the electromotive force desired, as is usual and well undcrstood. Although we prefer to insulate the layers v', the one from the other by asbestus paper, the same result will be in part attained by painting the iron composing the layers, and even were the layers superposed wit-hout any snch precaution a better result would be obtained than when the armature is made solid and not stratified, as described. ln place oi' winding in the manner shown at Fig. 4, the, winding may be in zigzag torni, as is illustrated by Fig.

Figs. 5, (i, and 7 show a complete continuous-current machine. ai is the armature, already described. Z Z are the cores ofthe electro-magnets, with a strong cast-iron backing, m m. lhe cores are grooved, as shown at l, and the grooves are iilled with sheet iron, either painted or insulated with asbestus paper. n n are the exciting-coils, the connections ol which are so arranged that t-he poles are alternately north and south, and so that opposite to each north pole we have a south pole. a is the commutator. In place of forming the cores of the electro-magnets ot' castiron, they maybe made l'rom sheetiron coiled and more or less insulated, and slotted to receive the coils, as described in respect to the armature.

The framing of thev machine will be understood by inspection of the drawings.

Figs. S, 9, and l0 show a complete alternating-current machine with permanent magnets. m is the armature. Z Z are. the steel magnets, ea r ried in two brass frames, m m, attached to the cast-iron trame m m. a a are the terminals oitthe armature-coils, on which press the rot lecting-brushes b b.

Having thus described the nature oi' our invention and in what manner it is to be carried into effect, we claim- 1. rlhe combination ot' a dynamo electric machine, a commutator, a commutator brush or finger, and a resistance which is introduced into the circuit oli' the commutator-ln'ush before contact is broken with the commutatorplates.

2. The combination, substantially as set forth, ol' the commutatouplates, the eontat'tfingers, the shat't on which they are carried. t-he elongated co1it-act-iinger, and the resistance interposed between the sha'l't and said finger.

2l. The combination of an armature plate or disk composed of superposed rings or layers ot' iron Yformed with radial grooves or channels therein, and the armature-coils which are laid in said grooves, substantial] y as set t'orth.

4. The combination ot' an armature disk or plate composed of superposed rings or layers of sheet-iron with insulating material between them, and having radial grooves or channels in its face, with the armalnne-coils placed in said grooves in planes perpendicular, or nearly so, to the axis ot' rotation substantially as set tort-h.

5. An armaturedisk composed ot su pen posed layers or rings ol'i ron, and having radial grooves in its lace, suliistantiall y as il lnstrated in Fig. 4 ,in combination with the armaturewires wound in a zigzag manner or laid in the grooves, substantially as illustrated in said iig-ure.

6. The herein-described magnet-core, l'ormed with slots or grooves in its face, in which insulated pieces oi' iron are inserted, 'tor the purpose set i'ort-h. p

7. The combination, substantially as set forth, ot the armature-pulley, the supcrposed layers or rings ot'sheet-iron, the armatm-e-coil, wound or laid in grooves formed in the l'aec ot the superposed sheet-iron layers, and the bolts 7c, which hold the layers ol' iron together.

.lOl-1N HO'PKINSON. ALEX. MU] ltlllCAl).

Titnessesz .TonN DEAN, J'. YVArr'r,

130171 of f1.7 (h'acmfmrrz lil/reef, London.

IOO 

